Scavenging-pump for internal-combustion engines.



APPLICATION FILED SEPT- 3. 19M.

Patented Feb. 13, 1917.

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'SCAVENGING PUMP FOR INTERNAL COMBUSTION ENGINES.

APPLICATION FILED SEPT- 3, I914.

Patented Feb. 13, 1917.

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Witnesses:

UNITED STATES PATENT OFFICE.

BERNHARD KRAMER, OF CHARLO TTENBURG, GERMANY, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CQRPORA'IION OF NEW YORK.

SCAVENGING-PUMP FUR INTERNAL-COMBUSTION ENGINES.

Application filed September 3, 1914.

To all whom it may concern:

Be it known that I, BERNHARD KRAMER, a subject of the Emperor of Germany, residing at Charlottenburg, Germany, have invented certain new and useful Improvements in scavenging-Pumps for Internal- -Combustion Engines, of which the following is a specification.

This invention relates to that class of internal combustion engines in which a scavenging pump is provided to furnish a charge of air to expel from the cylinders the proclucts of combustion and to furnish a supply of oxygen for burning the next charge of fuel. Ordinarily, piston pumps are used to supply the air, and they are driven by mechanical connection with the engine so that, working in synchronism therewith, and always compressing the same volume of air per stroke, they supply to the engine cylinders at all speeds a suflicient charge in amount and pressure. Thus, even at starting, ignition will quickly occur and the en- 1 gine begins working very soon.

Piston pumps, however, are liable to contaminate the compressed air with oil, so that rotary pumps, and especially those of the centrifugal type, seem to be preferable. But at low velocities these pumps do not deliver the air at suflicient pressure and quantity, so that in starting the engine the combustion in the cylinders will be slow in beginning. This lag in the action of the air pump is particularly noticeable when the pumps are driven electrically by a motor fed from a generator coupled to the combustion engine. In this case, the generator coupled tothe engine must be brought up to a certain speed before the motor can drive the pump at an effective rate.

My invention has for its object the provision of a scavenging pump system, for a multicylinder combustion engine, which will be prompt in starting and reliable in operation. Two features are prominent in this system; the first being means for varying the number of working cylinders connected to the pump, and second, the combination with a direct driven generator of a storage battery for furnishing current for the electric motor at starting. At starting, the charge delivered by the air pump is sup plied at first only to one or a few of the engine cylinders, but as the speed of rota- Specification of Letters Patent.

Patented Feb. 13, 1917.

Serial No. 860,028.

tion rises, and the delivery of the pump increases, additional cylinders are successively brought into service by suitable means until all are at work. The battery meanwhile furnishes current to the motor until the speed of the direct driven generator becomes sufficient to give a suitable current for driving the motor, when an automatic switch cuts out the battery and cuts in the generator, at the same time sending current through the batterytorecharge it.

In the accompanying drawings, Figure 1 is a sectional elevation of a portion of a multicylinder combustion engine equipped with an electrically driven centrifugal scavenging pump; Fig. 2 is a crosssection showing the hand-operated valves for cutting off the air from each cylinder; Figs. 3 to 6 show diagrams of electric circuits for con necting the generator, storage battery and motor.

The engine illustrated is a high pressure internal combustion engine of the multicylinder type, in which each cylinder 7 has two pistons 8, 9 working in opposite directions. My invention is not limited, however, to this specific arrangement. The lower or inner piston 8 is connected by the rod 10 to a crank in the shaft 11. The upper or outer piston 9 is connected to a cross-head 12, from whose ends long connecting rods 13 run down to cranks lt in the shaft 11. This upper piston controls the exhaust ports 15,

while the lower piston opens and closes the ports 16 which admit the scavenging and charging air. These ports are also controlled by an annular valve 17 encircling the cylinder, and moved by suitable means, as for example by hand-operated mechanism, such as a segment rack 18, pinion 19 and hand wheel 20. By means of this valve, the air can be shut off from or admitted to the cylinder preferably at the will of the attendant. 1

When open, the ports 16 communicate with a receiver 21 which is supplied with air from the centrifugal pump 22, preferably of the multi-stage type, and driven by the electric motor 23. The connecting rods 13 for the outer piston pass through flattened tubes 24 extending vertically through the receiver.

The motor is normally supplied with current from a generator 25 preferably directly driven by the engine. A simple arrange ment is shown in Fig. 3, in which both the generator and the motor are series wound, and the series field and armature of the motor are connected in series with the field ot the generator and directly across its terminals. By this arrangement the output or speed of the motor 23 will depend directly upon that of the generator 25.

Another system of circuits, in which shunt machines are employed, is shown in Fig. i. The field coils 26, 27 or" thegenerator and motor respectively are preferably arranged in parallel and are energized from a storage battery 28 during the starting operation; the armature of the motor 23 being connected directly across the terminals of the armature oi the generator 25. Leads 29, 3O connect the terminals of the generator with the battery terminals, the circuit being controlled by a double pole switch 31, preferably of the mercury cup variety, whose bridging contacts 32 are actuated by an electromagnet 33 having two opposed windings 34, 35. The winding 3% is constantly closed across the battery, and tends to hold the switch open. The other winding 35 is connected across the generator leads 29, 30 and opposes the winding 34:, so that when the generator attains a predetermined speed, the current in the coil 35 will overcome that in the coil 34 and cause the demagnetization of the magnet and the consequent closure of the switch by the dropping of the armature 36. The spring 37 is not strong enough to open the switch but only serves to counterbalance the greater part of the weight of the bridging contacts 32 and the armature 36. Then the switch closes, the gen erator current will energize the field coils 26, 27 and may also be utilized to recharge the storage battery. The switch 31 may be opened; 2'. 6., returned to the position shown in the drawing by any suitable means, for example, manually. When the switch is opened, the magnet 35 will then be deenergized and magnet 34:, which is connected with the battery 28, will act to maintain the switch in the open position.

In order to utilize the battery current for starting the motorwhen the engine is start- -ed, and thus bring the air pump up to the proper number of revolutions in a short time, the circuits shown in Fig. 5 may be adopted. Here the motor armature is connected with the generator through the switch 31, and the storage battery is connected across the motor terminals, with a hand switch or rheostat 38 in the circuit.

In starting, the battery energizes the armature and field coil of the motor, and also the field coil of the generator. When the generator comes up to normal speed, magnet coil 35 is energized and the switch 31 automatically cuts the generator into circuit with the motor, and the battery will be re charged, said motor and battery being in multiple relation.

Fig. 6 shows another system in which the storage battery is cut out of circuit after the generator reaches its normal voltage. To accomplish this result the switch has an additional bridging contact 38 which open-circuits the battery when the generator current causes a closure of the two upper contacts.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown is only illustrative, and that the invention can be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. The combination with a multicylinder high compression internal combustion engine, of an electrically driven scavenging e pump, a generator driven by the engine for supplying current to drive the pump, and means for limiting the number of cylinders to be charged with air on starting the engine.

2. The combination with'a multicylinder high compression internal combustion engine, of a scavenging pump, a motor for driving it, a generator driven by the engine, a storage battery in circuit with the generator and the motor, and means for limiting the number of cylinders to be charged with air on starting the engine.

3. The combination with a multicylinder high compression internal combustion engine, of a centrifugal air pump, a motor for driving it, a generator driven by the engine, a storage battery in circuit with the generator and motor, and means for limiting the number of cylinders taking air at startin 4. The combination with a multicylinder high compression internal combustion ens gine, of a centrifugal air pump, and means for varying the number of cylinders connected to said pump.

5. The combination with a multicylinder high compression internal combustion engine, of an electrically driven centrifugal air pump, a generator driven by the engine, and means for varying the number of cylinders connected to said pump.

6. The combination with a multicylinder high compression internal combustion engine, of a centrifugal air pump, an electric motor for driving it, a generator driven by the engine, a storage battery, and an automatic switch for cutting in the generator at a predetermined speed thereof.

7. The combination with a multicylinder high compression internal combustion engine, of a centrifugal air pump, an electric motor for driving it, a generator driven by the engine, a storage battery, and an automatic switch for cutting in the generator at a predetermined speed thereof, and also for cutting out the battery at the same time.

8. The combination with a multicylinder high compression internal combustion engine, of a rotary air pump, a receiver connected therewith and with the engine cylinders, and a valve at each cylinder for controlling the admission of air thereto independently of the operation of the engine.

9. The combination with a multicylinder high compression internal combustion engine, of a rotary air pump, a receiver connected therewith and with the engine cylinders, a valve at each cylinder for controlling the admission of air thereto independently of the operation of the engine, and means for operating said valve by hand to out said cylinder out of or into communication with said receiver at will.

10. The combination of an internal combustion engine having scavenging and exhaust ports, a generator driven thereby, a centrifugal air pump for supplying air under pressure to the scavenging port, an electric motor for driving the centrifugal Copies of this patent may be obtained for five cents each, by addressing the pump, said motor being disconnected from the generator when the engine is idle, and means for automatically connecting the motor to the generator when a predetermined speed is reached.

11. The combination of an internal combustion engine having scavenging and exhaust ports, a generator driven thereby, a centrifugal air pump for supplying air under pressure to the scavenging port, an electric motor for driving the centrifugal pump, a secondary battery connected to the motor for operating it upon starting the engine, and means connecting the generator to the motor when a predetermined speed is reached.

1?. The combination of an internal combustion engine, an air pump for delivering air to the engine, a dynamo driven by the engine, a motor in driving relation to the pump, a storage battery, and means for alternately connecting said motor with the dynamo and with the storage battery.

In witness whereof, I have hereunto set my hand.

BERNHARD KRAMER. Witnesses:

HEINRICH DECHAMPS, FRANZ O. GRANN.

Commissioner of Patents,

Washington, D. G. 

